Undercut crankshaft hardening coil

ABSTRACT

Improved induction heating methods are presented for induction hardening undercut fillets of crankshafts or other workpiece recesses or undercuts in which an active turn is energized to induce current in a passive turn translated toward a workpiece undercut for heating the undercut.

REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 12/484,422, filed Jun. 15, 2009, now U.S. Pat. No. 8,178,038, and claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 61/061,371, filed Jun. 13, 2008, entitled IMPROVED UNDERCUT CRANKSHAFT HARDENING COIL, the entireties of which applications are hereby incorporated by reference.

FIELD OF THE INVENTION

The present disclosure relates generally to the induction heating and more particularly to improved undercut crankshaft hardening coil apparatus and methods for hardening undercut crankshafts.

BACKGROUND

Modern large crankshafts for use in locomotives or other high torque applications are often undercut into the side wall, creating a recess. Although this offers an improved crankshaft for the application it presents a difficult challenge to properly heat treat the surface of the undercut. Descriptions of the undercut crankshaft hardening applications are found in U.S. Pat. Nos. 6,399,928 by Gezarzick et al and 7,145,115 by Zahn et al., which are incorporated herein by reference. Those disclosures required complex electrical connections and or coil configurations to engage both the undercut fillets and the journal to allow the part to be heated with one continuous process.

SUMMARY

One or more aspects of the disclosure are now summarized to facilitate a basic understanding of the disclosure, wherein this summary is not an extensive overview of the disclosure, and is intended neither to identify certain elements of the disclosure, nor to delineate the scope thereof. The primary purpose of the summary, rather, is to present some concepts of the disclosure in a simplified form prior to the more detailed description that is presented hereinafter. The present disclosure relates to improvements in induction heating coil assemblies and methods for induction hardening undercut fillets which may be employed for hardening crankshafts or other workpieces having recesses with undercut areas. The disclosed apparatus provides an active turn for heating a journal area in the workpiece recess and one or more passive turns which are translated toward undercut fillets after the coil assembly is moved toward the recess with coupling portions of the passive and active turns coupling energy from the active turn to the passive turn(s) for heating the undercut fillets.

In accordance with one or more aspects of the disclosure, an induction coil apparatus is provided, having a coil assembly comprised of an active turn and one or more passive turns. The active turn is coupleable to an electric power source to form a first conductive circuit including one or more active coupling sections and one or more crossover sections. When the assembly is located near a workpiece and energized, the crossover section(s) heat at least a portion of a journal area in a workpiece recess. The passive turn is electrically isolated from the active turn and forms a second conductive circuit including at least one passive coupling section and at least one passive heating section. The passive turn is translatable relative to the active turn between a first position for engaging with or disengaging from the workpiece in which the passive heating section clears a recess sidewall, and a second position in which the passive coupling section is proximate to and electromagnetically coupled with the active coupling section of the active turn and in which the passive heating section is located proximate to an undercut fillet area of the workpiece recess. In the second position, energy from the active turn is electromagnetically coupled to induce current in the passive turn(s) for fillet heating while the journal area is heated by the active turn.

In certain embodiments, the active turn includes a circumferential active heating portion proximate the journal area.

In certain embodiments, the passive turn is translatable relative to the active turn in a direction parallel to a longitudinal axis of the workpiece between the first and second positions.

In certain embodiments, an insulator is disposed between the passive coupling section and the active coupling section.

In certain embodiments, the passive heating section of the passive turn is located at least partially within the undercut fillet area of the workpiece recess in the second position.

Further aspects of the disclosure provide a method for hardening undercut fillets of a workpiece using induction heating. The method includes translating a coil assembly radially toward a recess in the workpiece such that a passive turn of the coil assembly clears a sidewall of the recess and at least one crossover section of an active coil of the coil assembly is proximate a journal area in the workpiece recess, translating the passive turn relative to the active turn such that a passive coupling section of the passive turn is proximate to and electromagnetically coupled with an active coupling section of the active turn and a passive heating section of the passive turn is located at least partially within an undercut fillet area of the workpiece recess, and energizing the active turn with electrical power to heat at least a portion of a journal area in the workpiece recess using the at least one crossover section of the active coil and to induce electrical current in the passive turn to heat at least a portion of the undercut fillet area of the workpiece recess using the passive heating section of the passive turn. In certain implementations, translation of the passive turn relative to the active turn comprises translating the passive turn in a direction parallel to a longitudinal axis of the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and drawings set forth certain illustrative implementations of the disclosure in detail, which are indicative of several exemplary ways in which the principles of the disclosure may be carried out. The illustrated examples, however, are not exhaustive of the many possible embodiments of the disclosure. Other objects, advantages and novel features of the disclosure will be appreciated from the following detailed description of the disclosure when considered in conjunction with the drawings, in which:

FIGS. 1-4 are partial perspective, side and end elevation, and top plan views illustrating conductor portions of an exemplary coil assembly with an active turn and two passive turns in extended second positions in accordance with one or more aspects of the present disclosure;

FIG. 5 is a simplified end elevation view of the coil assembly of FIGS. 1-4 illustrating the passive turns in first retracted positions for clearance during radial insertion to or extraction from a workpiece recess;

FIG. 6 is a simplified end elevation view of the coil assembly of FIGS. 1-5 illustrating the passive turns in second extended positions for undercut fillet heating;

FIG. 7 is a simplified partial end elevation view of the coil assembly of FIGS. 1-6 with the passive turns in first retracted positions illustrating insertion of the assembly into a recess of a crankshaft workpiece;

FIG. 8 is a simplified partial end elevation view of the coil assembly of FIGS. 1-7 illustrating the passive turns axially extended to second positions for induction heating of the undercut fillet areas of the workpiece recess;

FIG. 9 is a simplified partial end elevation view of the coil assembly of FIGS. 1-8 illustrating the position of an exemplary crossover portion of the active turn proximate a journal portion of the workpiece recess during induction heating;

FIGS. 10 and 11 are partial side and end elevation views of the coil assembly of FIGS. 1-9 illustrating magnetic laminations installed for electromagnetic coupling and further details of an exemplary support structure;

FIG. 12 is a simplified end elevation view of another exemplary embodiment of the coil assembly with a single passive turn in a first retracted position for clearance during radial insertion to or extraction from a workpiece recess for heating single undercut fillets;

FIG. 13 is a simplified end elevation view of the coil assembly embodiment of FIG. 12 illustrating the passive turn in a second extended position for undercut fillet heating;

FIG. 14 is a simplified partial end elevation view of the coil assembly of FIGS. 12 and 13 with the passive turn in the first retracted position illustrating insertion of the assembly into a recess of a crankshaft workpiece;

FIG. 15 is a simplified partial end elevation view of the coil assembly embodiment of FIGS. 12-14 illustrating the passive turn axially extended to a second position for induction heating of the undercut fillet area of the workpiece recess;

FIGS. 16 and 17 are partial end elevation views illustrating another coil assembly embodiment in which the passive turns are pivotally translatable between first retracted positions for insertion or removal and second extended positions for undercut fillet heating in accordance with the disclosure.

DETAILED DESCRIPTION

Referring now to the figures, several embodiments or implementations are hereinafter described in conjunction with the drawings, where like reference numerals are used to refer to like elements throughout, and where the various features are not necessarily drawn to scale. The present disclosure provides apparatus 2 and coil assemblies 4 thereof having an active turn 10 that couples with one or more fillet hardening passive turns 20, 21 and couples with a workpiece journal for hardening the journal 102 and also providing the energy to the two passive turns or coils to harden one or more undercut fillet areas 104 of the workpiece 100. The disclosed approach advantageously locates the active turn crossovers 10 c, 10 e so as to inductively heat the journal 102, and the active turn 10 can extend around a circumferential portion of the journal by up to about 180 degrees. The active turn 10, moreover, is electrically connected to a power supply to conduct current from the supply for inductively heating the journal 102 via the crossovers. One or more inner passive turns 20, 21 are provided in at least one space within and/or below the active turn 10 in certain embodiments, where the passive turns 20, 21 are passively energized via electromagnetic coupling from the active turn 10 such that the passive turns 20, 21 are not connected to the power supply, where the passive turns 20, 21 each form a closed loop structure. A coupling portion 20 a, 21 a of each passive turn 20, 21 is proximate the circumferential and/or other coupling portion 10 b, 10 f, 10 d of the active turn 10 so as to electromagnetically couple therewith, and a second portion 20 c, 21 c of the passive turn 20, 21 is extendable at least partially into an undercut of a fillet 104 for heating thereof. In certain journal portions 104 of a crankshaft workpiece 100 having two undercut fillets 104 at two axially spaced sides of the journal 102, each side can have one or more passive heating turns or turn portions for heating the associated fillet 104, with the passive turns 20, 21 of each side being axially movable at least partially into the undercut fillet areas 104 after radial approach of the coil arrangement 2 to or proximate the journal 102.

Referring initially to FIGS. 1-11, an exemplary induction coil apparatus 2 is illustrated, which may be advantageously employed for hardening undercut fillets 104 of a crankshaft or other workpiece 100. One embodiment is best shown in FIGS. 1-4, where the apparatus 2 has a coil assembly 4 including an active turn or coil 10 and two passive turns or coils 20 and 21. The active turn 10 is coupleable using conductive couplings 11 and 12 to an electric power source to form a first conductive circuit therewith, where the active turn is formed of hollow copper tube structures to provide an internal fluidic path for circulation of coolant during operation via the couplings 11 and 12. Likewise, the first and second passive turns 20 and 21 are formed of conductive (e.g., copper) tubes providing internal coolant passageways for coolant circulated via coolant couplings 40. The active turn 10 of FIGS. 1-11 is formed of sections 10 a-10 g including active coupling section 10 b, a first active crossover section 10 c, a second active coupling section 10 d, a second crossover section 10 e, another partial coupling portion 10 f and a final portion 10 g, where the crossover sections 10 c and 10 e are operative to heat all or a portion of the workpiece journal area 102 in a recess 110 thereof when the coil assembly 4 is positioned at or near the workpiece 100, as shown in FIG. 9.

The first passive turn 20 is electrically isolated from the active turn 10 and forms a closed conductive circuit including a circumferential coupling section 20 a, a crossover portion 20 b, a passive heating section 20 c, and a second crossover portion 20 d connecting back to the coupling portion 20 a. Similarly, the second passive turn 21 forms a closed conductive circuit electrically isolated from the active turn 10 via coupling section 21 a, crossover sections 21 b and 21 d and an outlying heating section 21 c, and the passive turns 20 and 21 are separately cooled by fluid provided via tubes 40. The active and passive turns 10, 20, and 21 are fitted with lamination keeper structures 30 for laminations 42 (FIGS. 10 and 11) for electromagnetic coupling of the active turn 10 with the passive turns 20 and 21, where any suitable magnetic material may be used for the laminations 42, such as iron in one embodiment. Other embodiments are possible using suitable magnetic material to form flux concentrator structures 42, which need not be laminations. As shown in FIGS. 10 and 11, moreover, the coil apparatus 2 further includes protective outer covers 50 and may include other suitable mounting and support structures for translation operation as described herein.

Referring also to FIGS. 5-9, the passive turns 20 and 21 are translatable by any suitable mechanical translation devices (not shown) relative to the active turn 10 between a first position (FIGS. 5 and 7) in which the passive heating sections 20 c and 21 c clear sidewalls 108 of a workpiece recess 110 as the coil assembly 4 is translated radially toward the recess 110 (FIG. 7) and a second position (FIGS. 6 and 8 in which the passive coupling sections 20 a, 21 a are proximate to and electromagnetically coupled with the first active coupling section 10 b, 10 f, 10 d of the active turn 10. As shown in FIG. 8, moreover, an insulator 26 may be provided in certain embodiments between the passive coupling section 20 a and the active coupling section 10 b, 10 f, as well as between the active coupling section 10 d and the passive coupling section 21 a of the second passive turn 21, which may be any suitable insulator material, such as Teflon in one example. In the second positions, moreover, the first passive heating section 20 c is located at least partially within a first undercut fillet area 104 of the workpiece recess 110, and the second passive heating section 21 c is located at least partially within a second undercut fillet area 104 of the workpiece recess 110, as illustrated in FIG. 8. In addition, as shown in FIG. 9, the active turn crossover portions 10 c and 10 e are disposed to be proximate the workpiece journal portion 102 during induction heating when the apparatus 2 is translated toward the recess 110.

In the embodiment of FIG. 8, the first passive turn 20 is translatable relative to the active turn 10 in a first direction (to the left in the figure) generally parallel to a longitudinal workpiece axis 8 between the first and second positions, and the second passive turn 21 is translatable in a generally opposite axial direction (to the right) between its first and second positions, where any suitable mechanism(s) can be used to provide the translation of the passive turns 20, 21 relative to the active turn 10.

The current in the closely coupled fillet hardening active turns 20, 21 will be equal (except for leakage flux) and opposite to the current in the main active turn 10 in the illustrated embodiments. As a result, the current in the fillet hardening portions 20 c and 21 c is in the same direction as the main driving current of the active turn 10, and the current induced in the fillets 104 is in the same direction as the main journal hardening current of the active turn crossover portions 10 c and 10 e so that the net electromagnetic configuration is that of a standard crankshaft hardening coil. With this arrangement, the fillet hardening passive sections 20 c and 21 c can be freely moved, at least partially, into and out of the fillet without any external electrical connection. As shown in FIG. 11, moreover, bumpers or guides 52 may be provided in the apparatus 2 for locating the apparatus 2 relative to a workpiece 100, which will generally be rotated about the axis 8 during heating with the active turn 10 energized. In addition, the apparatus and the coil assembly 4 thereof may extend any circumferential distance about the workpiece 100, such as about 180 degrees or less in various embodiments.

Referring now to FIGS. 16 and 17, the translation of the passive turns 20 and 21 need not be strictly parallel to the workpiece axis 8. In the embodiment of FIGS. 16 and 17, the passive turns 20 and 21 are pivotally translatable between first retracted positions for insertion or removal of the apparatus 2 while clearing the sidewalls 108 (FIG. 16), and second extended positions for undercut fillet heating (FIG. 17).

Referring now to FIGS. 12-15, another exemplary embodiment of the coil assembly 4 is illustrated, having a single passive turn 20 configured generally as described above, along with an active turn 10 similar to that shown in the above figures, but with the section 10 d being lowered to be proximate the journal 102, such as approximately the same proximity as turn 20 c, in order to force the current to return through the journal 102. This embodiment may be employed for hardening recesses 110 having only one undercut fillet 104, which is heated via the translatable passive turn portion 20 c, while the journal 102 is heated via the active turn 10 as described in the above embodiments.

The above described apparatus 2 is particularly suitable for various induction heating processes. The disclosure provides an exemplary process for hardening undercut fillets 104 of a workpiece 100, which may employ the described apparatus 2 or which may be used in conjunction with other apparatus. The process includes translating a coil assembly 4 radially toward a recess 110 in the workpiece 100 such that a passive turn 20 of the coil assembly 4 clears a sidewall 108 of the recess 110 and at least one crossover section 10 c, 10 e of an active coil 10 of the coil assembly 4 is proximate a journal area 102 in the workpiece recess 110. The process also includes translating the passive turn 20 relative to the active turn 10 such that a passive coupling section 20 a of the passive turn 20 is proximate to and electromagnetically coupled with an active coupling section 10 b, 10 f of the active turn 10 and a passive heating section 20 c of the passive turn 20 is located at least partially within an undercut fillet area 104 of the workpiece recess 110, and energizing the active turn 10 with electrical power to heat at least a portion of a journal area 102 in the workpiece recess 110 using the at least one crossover section 10 c, 10 e of the active coil 10 and to induce electrical current in the passive turn 20 to heat at least a portion of the undercut fillet area 104 of the workpiece recess 110 using the passive heating section 20 c of the passive turn 20. In certain embodiments, the translation of the passive turn 20 relative to the active turn 10 comprises translating the passive turn 20 in a direction parallel to a longitudinal axis 8 of the workpiece 100.

The above examples are merely illustrative of several possible embodiments of various aspects of the present disclosure, where equivalent alterations and/or modifications will occur to others skilled in the art upon reading and understanding this specification and the annexed drawings. In particular regard to the various functions performed by the above described components (assemblies, devices, systems, circuits, and the like), the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component, such as hardware, software, or combinations thereof, which performs the specified function of the described component (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the illustrated implementations of the disclosure. In addition, although a particular feature of the disclosure may have been illustrated and/or described with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Also, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in the detailed description and/or in the claims, such terms are intended to be inclusive in a manner similar to the term “comprising”. 

The following is claimed:
 1. A method of hardening a workpiece using induction heating, the method comprising: translating a coil assembly toward the workpiece; translating a passive turn of the coil assembly relative to an active turn of the coil assembly such that a passive coupling section of the passive turn is electromagnetically coupled with an active coupling section of the active turn wherein translating the passive turn relative to the active turn comprises translating at least a portion of a passive heating section of the passive turn within an undercut area of a recess in the workpiece; and energizing the active turn with electrical power to induce electrical current in the passive turn to heat at least a portion of the workpiece using the passive heating section of the passive turn.
 2. The method of claim 1, wherein translating the coil assembly toward the workpiece comprises translating the passive turn and the active turn radially toward a longitudinal axis of the workpiece.
 3. The method of claim 2, wherein translating the coil assembly toward the workpiece comprises translating at least a portion of the passive turn into a recess in the workpiece.
 4. The method of claim 1, wherein the coil assembly is translated toward the workpiece such that at least a portion of the passive turn of the coil assembly clears a sidewall of a recess in the workpiece.
 5. The method of claim 1, wherein translating the coil assembly toward the workpiece comprises translating at least a portion of the passive turn into a recess in the workpiece.
 6. The method of claim 5, wherein translating the passive turn relative to the active turn comprises translating the passive turn in a direction parallel to a longitudinal axis of the workpiece.
 7. The method of claim 5, further comprising deenergizing the active turn and translating the coil assembly away from the workpiece after at least a portion of the workpiece has been heated using the coil assembly.
 8. The method of claim 7, further comprising translating the passive turn away from the recess of the workpiece prior to translating the coil assembly away from the workpiece.
 9. The method of claim 1, further comprising deenergizing the active turn and translating the coil assembly away from the workpiece after at least a portion of the workpiece has been heated using the coil assembly.
 10. The method of claim 9, further comprising translating the passive turn away from a recess of the workpiece prior to translating the coil assembly away from the workpiece.
 11. A method of hardening a workpiece using induction heating, the method comprising: translating a coil assembly toward the workpiece; translating a passive turn of the coil assembly relative to an active turn of the coil assembly toward an undercut area of a recess in the workpiece wherein translating the passive turn relative to the active turn comprises translating the passive turn in a direction generally parallel to a longitudinal axis of the workpiece; and energizing the active turn with electrical power to induce electrical current in the passive turn to heat at least a portion of the workpiece using a passive heating section of the passive turn.
 12. The method of claim 11, wherein translating the coil assembly toward the workpiece comprises translating at least a portion of the passive turn into the recess in the workpiece.
 13. A method of hardening a workpiece using induction heating, the method comprising: providing a coil assembly including an active turn and a passive turn electrically isolated from one another and translatable relative to one another; translating the coil assembly toward the workpiece while the passive turn is in a first position relative to the active turn such that at least a portion of the passive turn of the coil assembly clears a portion of the workpiece; translating the passive turn relative to the active turn toward at least one undercut area of the workpiece wherein the undercut area is a region that is recessed from at least one sidewall of the workpiece, the sidewall is generally parallel relative to a longitudinal axis of the workpiece; energizing the active turn with electrical power to induce electrical current in the passive turn to heat at least a portion of the workpiece. 